Method of and apparatus for repairing heated structures such as furnaces, retorts, or the like



Oct. 28, 1930. A, McD. DUCKHAM 1,780,120

METHOD OF AND APPARATUS FOR REPAIRING HEATED STRUCTURES sucH AS FURNACES, RETORTS, on THE LIKE Filed May 15, 1929 2 Sheets-Sheet 1 i9avezzibrv 0%?kar fifi'fi zr 5 g r I 5777/1, wrnei Oct. 28, 1930. A, McD, DUCKHAM 1,780,120

METHOD OF AND APPARATUS FOR REPAIRING HEATED STRUCTURES SUCH AS FURNACES, RETORTS, OR THE LIKE Filed May 15, 1929 2 Sheets-Sheet 2 Patented Get. 28, 1%36 s FAT ARTHUR MCDOUGALL DUCKHAM, OF LONDON, ENGLAND FURNACES, RETOETS, ORTHE LIKE Application filed May 15, 1929, Serial No. 363,396, and in Great Britain May 24, 1928.

The difficulty of repairing heated structures such as furnaces, retorts and the like by filling with jointing mixture cracks that may have developed in the structural material, is associated with the difficulty of locating the crack and causing penetration of the jointing mixture the crack. The position of the crack is generally indicated by a leak of combustible gas which becomes vis- 13 ible by an apearance of flame or by abnormal incandescence of surrounding brickwork due to surface combustion.

One known method of dealing with the crack consists in forcing jointing mixture by 5 air pressure from a container through a pipe directed on to the crack. The proportion of water that must be present in a mixture which will flow through a pipe is considerable, and before suflicient solid jointing material has been injected into the crack, cooling has occurred and the crack has become invisible, making continued injection difficult; such sudden cooling has, moreover, a deleterious effect upon the brickwork and, further, the

effect of applying such a dilute mixture is that the mixture is unnecessarily spread over the, surface andthe crack is bridged rat-her than entered, so that although it is temporarily stopped and disappears it is soon again leaking.

i This invention is based on the conclusion that the j ointingmixture should be less fluid than has hitherto been usual and should be injected into the crack by a single application which should suifice to. seal the crack by proper penetration of the mixture into it. To render this possible asufiicient quantity of the jointing mixture must be injected into the crack with accuracy, quickly and with great force.

This invention relates to a method of repairing heated structures of the kind in question by bringing a charge of jointing mixture substantially into register with the crack and then projecting the charge into the crack by means of a suddenly developed or released force. The charge should not exceed the quantity estimated as likely to be required to fill the crack, because in addition to being .such as wasted the excess would adhere to the surface ofthe structure forming protuberances to which there are Well-known objections.

It'Will be seen that the invention necessitates an apparatus which can be raised or lowered or thrust horizontally or otherwise into the furnace or retort by means of a carrying and guiding rod or the like, until opposite the crack to be filled, as contrasted with bringing the jointing mixture to the crack by means of a pipe leading from an apparatus outside the furnace.

The jointing material is preferably on closed in a container having a discharge orifi'ce which in operation. is brought into alignment with the crack to be sealed; a pressure p is suddenly created or released behind the mixture so that this is suddenly projected into the crack with great force.

The pressure may be created by any suitable means y an explosive or by the sudden release of suitable liquid or gaseous pressure. The discharge orifice may conveniently be aslot, considerably lon er than it is wide, formed by taperingsid zas, so that by turning the container one way or the other, either horizontal or vertical cracks may be filled by bringing the major axis of the slot parallel to the direction of the crack. The container is preferably attached to a rod made up of separatelengths in well-known manner, so that it can be lengthened or shortened. If desired, more than one means of support or suspension may be used so as to minimize or obviate any tendency of the container to swing, and to cause it quickly to come to rest. Incase the jointing mixture is to be projected by gaseous pressure created by the sudden expansion of a small charge of a compressed or liquefied gas placed in a container behind the charge of jointing mixture,'this container ,90 may be explosively burst or a cap sealing an aperture in the container may open by thermal effect. In the accompanying drawings,

Fig. 1 is an axial section,

Fig. 2 a plan, and

Fig. 3 an elevation of an apparatus, which may conveniently be called a cement gun, suitable for the invention.

'Fig. 4 is a vertical section, and

Fig. 5 is a plan of a double barrel gun for comparatively heavy work.

Referring to Figs. 13, the :yl ndrical metal casing a has a tube 5 extending through it for reception of a cement Container 0. The latter is conveniently a tube fixed to a breech (Z and charged with ointing mixture. The

breech contains an explosive cartridge 6 comprising a firing cap wh ch is substantlally 1n.

contact with the breech piece 7.

The discharge endof the container copens into a mouth piece 9 formed by two con-g verging plates fixed to one end wall of the casing In the other end wall are screwed two pins h, one of which is surrounded by a sleeve 2' constituting a distance piece. On to this pin is threaded the breech piece 'f-s'o that the latter can turn onthe pin,ra slot at the other end of the piece beingadapted'to engage the other pin it as indicated, ;..When the breech piece is thus engaged itextends across the open end ofthe breech and can be held firmly thereto by screwing'up the wing nuts The portion of the breech piece 'Which closes the open end of the-'breechis of a good conductor of heatyforinstance a copper inset f. V l ,7

The casing a is grippedby a strap Zh'aving a screw thread pin on for attachment offthe first length of rod which can be put together 1n lengths as requiredv vertical retort), that is tosay until the mouthpiece 9 is lengthwise substantially in alignmentwith the crackv to be filled. 'Whfen the casing has, been in position for afew seconds the heat of thestructurewill penetrate through the breech plate to the 'firing cap and explode the cap, thus suddenly and rapidly discharging thecement from the container 0 into the crack.

sThe jointingmixture commonly usedjis madevup with silicate of soda and, when charged into the container 0, becomes covered at'the end exposed to the air with a skin which sufiices to retain thecharge in the container until'firing occurs; 1 Referring now to Figs. 4c and'.5,;th e casing la carries trunnions. a mounted to revolve in i .-uprights 0 which spring from axles p having wheels q.

Fixed in the top andbottom of the casing are two containers 0 each closed at the upper end by a breech cl adapted to contain the cartridge 6 as explained in relation to Figs. 13. Fixed to the top of the casing are screwthreaded sockets 1" into Which screw the breech pieces f, in each of which there is iaicopper inset f, as described in relation toFigs. 1-3. The mouthpiece g is similar to that already described Oneof the 'trunnions a has an axial screw threaded bore into which can bescrewed the end of -the manipulatingrod.

To use the gun, the breech pieces are re? moved, .ithe cartridges' are inserted in the breeches, and the breechpieces are replaced.

The gun having been reversed on its axis-the known cementmixture is'charged into the containers 0. The cement '(especially when 'COIltZllIllIlg sodiumsilicate) rapldly becomes covered on its exposed surfaceby-a'sk-im, 'sufiicientlystrong to permit of the gun beiiig reversed onits axis without discharge ofthe cement. By means of-the rodthe gunis now wheeled onthe internal surface of the'retor't or furnace to the required position in twhi'ch the 'slotof the mouth 'g 'is-more or less 'in register with the crack to be sealed; slight oscillations of the gun-0n its axis being possible, if necessary, by straining the rod. After a few secondsythe heat of theturnac'e penetrates the copperdiscs 7" and-the-carthe mouthpiece into the slot.

the Walls ofthe heated structureunder repair In certain cases where the temperature of *ico tends-to fluctuate, diificulty, may be en tridges are fired to propel the cement through countered in regard to the-exact time -required to cause the firing of the'explosilve.

In such cases the guns may be'p'rovidedwith p a cap containing an electric resistance, the

circuit leads of which'extend through 'an insulating plugin the breech closure in place of the copper-inset, and through-therod'to a source of electric current under control of the operator. This mode of firinglthe, gun makes the method independentof-thetemperature of the retort Or -furnace. 1

' Having'thus described the 'nature-"of the said invention andthe best means I know for carrying the "same-into practical effect, I

claim z T c a '1. A method of repairing'a crack ina heated structure 'of'the kindreferred to which 7 consists in bringing a charge of'repairing material substantially into register with sa crack and applying a suddenlyfdeveloped charge to-project ityinto the force to the crack.

2. The method of repairing a crack in fa heated structure of the kind referredtowh-ich consists in bringing a quantityoi'g i'epairing material just sufiicientto fill :the' crack/to. be repaired substantially int'o.:register with the crack, and then applying suddenlyr'developed force to thecharge to proj ectisuch ate charge into the crack at a single application.

3. A method of repairing a crack in a heated structure of the kind referred to which consists in bringing a charge of confined repairing material substantially into register with a crack and then by a single suddenly developed force projecting the charge elongated transversely in one direction into said crack.

4. Apparatus for repairing a crack in a heated structure of the kind referred to comprising in combination a container for a charge ofrepairing material having an open mouth, means for holding an explosive charge in the container behind the charge of repairing material, means operable from the outside of the structure to be repaired for introducing the container into the structure and presenting its mouth substantially to a crack in the structure and means for exploding the explosive charge.

5. Apparatus for repairing a crack in a heated structure of the kind referred to comprising in combination a container for a charge of repairing material, said container having an open month, an elongated mouthpiece attached over said open mouth, a movable breech piece on the container rearwardly of said mouth, and means for holding an explosive charge in the breech piece in communication With the contents of the container.

6. Apparatus for repairing a crack in a heated structure of the kind referred to comprising in combination, a cylindrical casing having end pieces, a tube held between the end pieces to hold an open mouthed tubular container for repairing material, a breech piece carried by one of said end pieces and adapted to receive an explosive charge, means for holding the breech piece in position on said end piece, means for firing the explosive charge and a mouthpiece mounted on the other end piece of the said cylindrical casing.

7. Apparatus for repairing a crack in a heated structure of the kind referred to comprising an open ended container for a charge of repairing material, a movable breech piece on one end of the container and communicating with the interior of the latter means for holding an explosive charge in the breech piece, and means attached to the container for placing it in position in the structure to be repaired, said means being operable from the outside of such structure.

8. Apparatus for repairing a crack in a heated structure of the kind referred to comprising a tubular casing to contain a charge of repairing material, said casing having an open mouth at one end, a movable breech piece on the other end of said casing communicating with the interior thereof, means for holding an explosive charge in the breech piece, means attached to the container for placing it in position in a structure to be repaired and ARTHUR MoDOUGALL DUCKHAM. 

